Multi-Stage Absorber Vessel for CO2 Capture
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Solution Overview
Problem
Existing carbon dioxide capture systems using ammonia-based absorption face issues with plugging due to the formation of solids like ammonium carbonate and bicarbonate, which deteriorate system performance.
Innovation Solution
A multi-stage absorber vessel with separate sump vessels is used to recycle ionic solutions under varying conditions, allowing for the formation and separation of solids, thereby reducing plugging and enhancing CO2 capture efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-stage chilled ammonia-based absorption system is used for CO2 removal, then the system structure is simple, but solids formation causes plugging and deteriorates system performance
Solution Approach 1:
The absorber vessel is divided into multiple absorption stages (first absorption stage, second absorption stage, etc.) with separate sump vessels for each stage. This segmentation allows different stages to operate under different conditions and enables selective recycling of ionic solutions, preventing solid formation in the mass transfer device while maintaining simple overall system structure.
Solution Approach 2:
Different absorption stages are configured with different ionic solution conditions (different temperatures, different NH3-to-CO2 ratios) to create local quality variations. The first absorption stage operates under conditions favoring solid formation for high CO2 capture, while subsequent stages operate under conditions preventing solid formation, thus eliminating plugging issues in specific locations.
2Productivity
If multiple absorption stages operating at different temperatures and NH3-to-CO2 ratios are implemented, then CO2 capture efficiency is improved, but device complexity increases
Solution Approach 1:
Multiple absorption stages are merged into a single absorber vessel with internal separation zones, eliminating the need for multiple separate vessels. The sump vessels are integrated into the absorber structure, combining multiple functions (CO2 absorption, solid separation, ionic solution recycling) into one unified device while maintaining high CO2 capture efficiency.
Solution Approach 2:
The absorber vessel serves multiple functions simultaneously: CO2 absorption from flue gas, separation of solids from ionic solution, conditioning of ionic solution for different stages, and recycling of lean ionic solution. This multi-functionality reduces the need for additional equipment while achieving high CO2 capture efficiency.
3Loss of substance
If ionic solution is recycled from lower absorption stages to upper stages, then ammonia slip is reduced, but solid deposition may occur in the absorber vessel
Solution Approach 1:
The system performs preliminary separation of solids from the ionic solution in the sump vessels before recycling the lean ionic solution back to the absorption stages. This preliminary action removes solids that would cause deposition in the absorber vessel while maintaining the beneficial ammonia recycling that reduces ammonia slip.
Solution Approach 2:
Solids are extracted from the ionic solution stream in the sump vessels through gravity separation and filtration before the ionic solution is recycled. This extraction removes the harmful solid particles that would cause deposition, while the filtered ionic solution continues to recycle and reduce ammonia slip.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively captures CO2 from flue gas streams with reduced ammonia slip and improved CO2 carrying capacity, minimizing operational issues and maintaining high capture efficiency.
Implementation Method 1
The ionic solution is put into contact with the flue gas stream via a gas-liquid contacting device (hereinafter, mass transfer device, MTD) used for mass transfer... Once contacted with the flue gas stream, the ionic solution acts to absorb CO2 from the flue gas stream
Implementation Method 2
The rich ionic solution is then regenerated via a regenerator system to release the CO2 absorbed by the ionic solution from the flue gas stream... The CO2 released from the ionic solution may then be output to storage or other predetermined uses/purposes
Data Source
AI summary
A system for removing carbon dioxide from a flue gas stream is provided, the system comprising an absorber vessel configured to receive a flue gas stream, the absorber vessel comprising a first absorption stage configured to receive the flue gas stream and contact it with a first ionic solution, a second absorption stage configured to receive flue gas which has passed the first absorption stage and contact it with a second ionic solution, a first sump vessel, and a second sump vessel. Furthermore, a method for removing CO2 from a flue gas stream containing CO2 is provided, the method comprising the steps of a) contacting a flow of a first ionic solution comprising NH3 with a flue gas stream to remove a first portion of CO2 from the flue gas stream, b) collecting the used ionic solution from step a) in a first sump vessel, c) recycling ionic solution from the first sump vessel to step a), d) contacting a flow of a second ionic solution comprising NH3 with the flue gas stream to remove a second portion of CO2 from the flue gas stream, e) collecting the used ionic solution from step d) in a second sump vessel, and f) recycling ionic solution from the second sump vessel to step d).